Rigby is a small city in and the county seat of Jefferson County, Idaho, United States. The population was 3,945 at the 2010 census, up from 2,998 in 2000. The larger "Rigby area" includes such outlying unincorporated communities as Annis, Garfield, Grant, Labelle, and Clark. Other nearby incorporated areas within Jefferson County include Menan, Roberts, Lewisville, and Ririe.